Musnad Ahmad 907:116

'Abd al-Rahman ibn Mahdi narrated to us, from Sufyan, from 'Abd al-Malik ibn 'Umayr, from Jabir ibn Samurah, who said: I came with my father to the Prophet, peace and blessings of Allah be upon him, and he was saying: "This matter will continue to be righteous until there are twelve amirs." Then he said a word I did not understand. I said to my father: "What did he say?" He said: "All of them are from Quraysh."